In general, dock seals and shelters address the need to prevent the ingress of outdoor environmental conditions or contaminants (e.g., rain, snow, wind, hot/cold temperatures, insects, animals, etc.) into the interior of a building (e.g., the dock area) and cargo area of a vehicle during the loading or unloading of the vehicle. Dock shelters and seals also address the need to prevent the egress of conditioned air from within a building and/or a vehicle cargo area to the outdoor environment. The design of dock seals and shelters that effectively isolate the interior space of a building and adjacent vehicle cargo area from the outdoor environment is complicated by the fact that vehicles (e.g., the trailer or rear portion of a truck) may not be centered relative to the seal or shelter when backed into the seal or shelter. As a result, dock seals and shelters are typically designed to compensate for some range of off-center vehicle positions within which the functionality of the seal or shelter is not compromised. Further, the structures of a seal or shelter, particularly side members, are desirably capable of recovering from repeated impacts from the rear portions of off-center vehicles without sustaining substantial permanent deformation.
Some known dock seals use side members having a compressible foam core or body surrounded by a coated fabric or vinyl outer layer. The foam core provides sufficient structural rigidity to enable the side members to be extended a short distance from the building wall surrounding the loading dock. The coated fabric outer layer protects the foam core from outdoor environmental conditions (e.g., moisture), provides wear resistance to repeated impacts from the rear portions of vehicles, and may provide desirable aesthetic qualities. Additionally, a header structure may span between the side members along a top portion of the loading dock opening. The header structure may be another compressible member similar in construction to the side members and, in some cases, may include a weighted fabric curtain that hangs downwardly to contact the top of a truck trailer to form an environmental barrier along the top of the trailer.
Another type of dock seal uses inflatable side members and a header structure having internal compressible resilient pads, which provide some degree of side member compressibility when the side members are in a deflated condition. In either case, when the rear portion of a vehicle (e.g., a truck trailer) is backed into either foam or inflatable dock seal side and header members, the side and header members are compressed toward the building wall to form a seal along the lateral and top back edges of the vehicle. If present, the head curtain sweeps along the top of the trailer to form a seal at the top of the trailer between the side members. Dock seals typically consume a relatively small amount of wall space and can provide a relatively high quality seal between the rear edges of a vehicle and the outside building wall surrounding the dock. However, when the dock seal side members are compressed, they may be displaced into or otherwise encroach on the opening to the rear of the docked vehicle. As a result, the compressed side member may interfere with operation of a fork lift and/or an operator during loading and unloading activities. In addition, inflatable dock seals are susceptible to power losses and tears that compromise the ability of the side members to inflate to provide an acceptable seal.
In contrast to dock seals, some known dock shelters use side members that are mounted to the outside building wall surrounding the loading dock. The side members are spaced well to the outside of the sides of a docked vehicle. The side members are configured to extend (i.e., to be cantilevered) an appreciable distance from the outside building wall, particularly in cases where a dock leveler protrudes from the dock opening. The side members may also support flexible seal members, which are often referred to as side curtains, extending inwardly from the side members across at least a portion of the opening defined by the side members. When a vehicle such as, for example, a truck trailer, is backed into the opening of the dock shelter, the inwardly facing edges of the seal members or side curtains resiliently deflect and sweep against the lateral sides of the trailer to form an environmental barrier therebetween. As with dock seals, dock shelters also typically include a header structure, which may include a head curtain, to form an environmental barrier along the top edge of the rear of the vehicle.
In contrast to dock seals, dock shelters typically provide unobstructed access to a vehicle cargo area opening (i.e., there are no foam pads or the like to be compressed and displaced into the opening). However, most known dock shelter side members are constructed using rigid wood, fiberglass or metal frames capable of supporting the significant weight of the seal members or side curtains, which are usually held at an appreciable distance (e.g., several feet) from the building wall. Such side members may be permanently deformed if they are impacted by a vehicle. Accordingly, bumpers or stops may be mounted to the lower edge of the dock shelter to prevent a vehicle (e.g., a truck trailer) from impacting and damaging the rigid shelter.
The rigid side members used to implement these known dock shelters are also typically mechanically coupled via the header and/or another rigid member to provide increased lateral rigidity to the dock shelter to minimize the ability of the side members to move from side-to-side. Because of this, the side members typically have to be mounted relatively far apart to accommodate a wide range of possible off-center vehicle positions. This relatively large distance between the rigid side members consumes a significant and, thus, expensive amount of building wall space for each loading dock opening.
More recently, dock shelters having impactable side members have been developed. The impactable side members are similar to those used with dock seals and typically use a foam core or body surrounded by a coated fabric outer layer. Seal members or side curtains, which may be constructed using a fabric and flexible fiberglass stays combination or a foam core and fabric combination, are typically mounted to the side members to extend at least partially across the shelter opening. When a vehicle is backed into the shelter, the inwardly facing edges of the seal members or side curtains deflect and sweep against the sides of the vehicle to form an environmental barrier or seal against the sides of the vehicle. In the event the off-center position of a vehicle results in the rear of the vehicle impacting a side member, the foam core or body of the side member is resiliently compressed. When the vehicle is pulled away from an impacted side member, the foam core of the side member causes the side member to substantially recover to its original condition or shape.
While dock shelters having compressible foam side members provide the advantages of unobstructed access to a truck trailer opening (at least when the side members are not impacted) and the ability to withstand repeated impacts from off-center vehicles, these more recent dock shelter designs still have some drawbacks. For example, the foam cores of the side members must be made relatively wide and bulky to support their own weight and the weight of the side seals or curtains. Also, the relatively bulky foam cores needed are expensive, difficult to mount to the wall surface and consume a significant amount of building wall space. In addition, the inherent structural characteristics of the foam core and fabric combination significantly limit the permissible weight of the side curtains and/or the distance at which the side curtains can be mounted from the wall without causing the side members to sag an unacceptable and perceptible amount.